1. Field of the Invention
The present invention relates generally to coaxial cable connectors. More particularly, the present invention relates to coaxial F-connectors adapted to enhance electrical continuity.
2. Description of the Related Art
Cable television systems and satellite television receiving systems utilize coaxial cable and coaxial cable connectors for distributing signals. As is known in the industry, coaxial connectors such as “F-Type” connectors are commonly used to terminate lengths of coaxial cable. Where an “F” type connector terminates a coaxial cable, a mating connector typically interconnects a device such as a splitter, set top box, or a cable splice.
An electrical junction formed by mated F connectors may be referred to as a “male” F connector mated with a “female” F connector. Where a female F connector is mounted on an item of equipment such as a set top box, it may be referred to as a port. And, where a male F connector is used to terminate a coaxial cable, a common feature of the male connector is use of an attached coaxial cable center conductor as the central or signal contact that mates with a corresponding female connector contact.
Coaxial cable includes concentric conductors in the form of a center conductor spaced apart from a surrounding outer conductor by a dielectric layer. While the center conductor may be a single wire, the outer conductor typically includes a grounding sheath conductor such as tubular sheath formed from braided wire. The braided sheath may overlay yet another ground conductor(s) such as a metallic foil that covers the dielectric. The electrical junction made when F connectors are mated therefore includes a first junction interconnecting center conductors and a second junction interconnecting outer or ground conductors.
Male F-connectors typically include a central post, a body, and a nut. Some of these connectors may further include a means for immobilizing a coaxial cable within the body.
The post provides an electrical conductor for contacting the coaxial cable braid or sheath. A tubular post with an insertable shank that can slide between a coaxial cable's outer braid or sheath and dielectric serves this purpose. Frequently, the shank has a barbed insertable end for enhancing electrical contact and/or mechanical attachment.
The nut is rotatably engaged with the post via an enlarged post end or a post flange opposite the shank. Where the nut of a male F connector is properly threaded onto an F female connector, the enlarged post end is brought into contact with a mating ground conductor such as the metallic body of an F female port. Unreliable and/or intermittent continuity is frequently the result of a loose nut and a ground circuit passing poorly or not at all from the post to an F female port.
Reliable grounding through direct post to port contact requires proper installation techniques in mating male and female connectors. For example, where a male connector includes a threaded nut, proper tightening/torqueing of the nut onto a mating connector is required. When properly installed, the male connector post directly engages an outer conductor of a female connector such as a port ground terminal and a direct electrical connection is established between the post and the ground terminal. If the installer fails to accomplish this, it is doubtful that a reliable or dependable electrical grounding path will be established between the coaxial cable sheath and the female connector.
Notably, F connector installation problems may come to light only after the installer has left the site. For example, operation of the connection may initially be reliable but later become unreliable due to changes such as oxidation and/or deformation of connector metal parts. Further, unintended gaps between metallic parts in the connection invites radio frequency (“RF”) signal ingress and egress that can interfere with or attenuate the signal the coaxial connection is intended to transport.
With growing demands of cable, satellite and broadband operators for more reliable signal distribution, it is, as stated by SCTE, “most desirable to have [connector] contact resistance as close to zero as possible.” (ANSI/SCTE 103 2012 Test Method for DC Contact Resistance, Drop cable to “F” connectors and F 81 Barrels). Notably, this requirement should be met along with others as they may be applicable, for example a nominal 75 ohm impedance, environmental seals such as moisture sealing, service life measured in years, tolerance to wide temperature extremes, cable/connector insertion and retention forces, and in cases more. (SCTE-103-2004 (DC contact resistance): ANSI/SCTE 60-2004 (Moisture Migration test): ASTM-B117-03 (Salt Spray test): ANSI/SCTE-99-2004 (Axial Pull test): SCTE-98-2004 (Tightening Torque): SCTE-73-2002 (Coaxial Insertion Force): SCTE-48-3-2004 (Shielding Effectiveness): ANSI/SCTE-04-1997 (F Connector Return Loss): SBCA standards of Physical Dimension Tolerance: GR-1503-core, Issue 1, March 1995 UV degradation).